M5 Headlight Rotator Bolts

[jordan]

has any one found a place to buy the tiny m8 I believe grade 8 head light rotator bolts?

[kwilford]

has any one found a place to buy the tiny m8 I believe grade 8 head light rotator bolts?

If you are referring to the three little bolts that connect the headlight bucket rotator "swivel strips" to the inner gear, they are M5 bolts. The other odd thing, aside from the Grade 10.9 (approximately equivalent to a SAE Grade 8) is the taller head on the OEM hex-head bolt. I found a better choice (as documented in my thread on GT headlight mechanism repairs) is to buy M5 Socket Head (Allen Head) Cap Screws, which are readily available in either Grade 10.9 or 12.9 from your local bolt supply store. Make SURE that they are the same length as the OEM bolts, as the rotator gear holes are NOT threaded all the way through. If the bolts are too long, they will either strip the bolt threads, or not fully tighten against the gear, which is turn will lead them to break again.

I have split these posts into it's own thread. HTH

[kwilford]

Almost forgot the most important fact. A #10-32 thread is IDENTICAL to the M5 thread. So you can also use SAE Grade 8 #10-32 socket head cap screws (or even just plain hex-head bolts) . HTH

[GTJIM]

#10-32 threads have 32 threads per inch or a pich equivalent to 0.79375mm
M5 X 0.8 threads have a pitch of 0.8mm - CLOSE to the same.
They fit because the thread angle is the same - 60 degrees and the diameter is also very close to the same.
But they ain't "the same"!
Use M5 X 0.8 cap screws - the holes ARE tapped M5 (DIN spec probably - GTs being German).
A tiny dab of "Super Nut Locker" Loctite (TM) helps stop them backing out at a later stage.

[Yoda]

I bought a box of these a while back (either 50 or 100), but unfortunately didn't have that many GT's to upgrade. If you need a few let me know.

[namba209 (R.I.P.)]

Keith, et.al., After long pondering about why the bolts break or are sheared off, and looking at my mechanism, I came to the conclusion that maybe the 3 roll pins are not engaging the spring plates, thereby causing the plates to shift radially and eventually cut into the bolts. Looking at it from an engineering point of view, it appears the bolts only hold the spring plates to the hub and the roll pins are designed to make the whole assembly rotate and take up the stress of the assembly stopping and starting. The pins are definately easier to replace than broken bolts. It could be the pins are driven too far into the hub to completely engage all the spring plates. Whatcha think?

[nobody]

Since I'm going down this road what happens is the bolts have a tendency to back out over time and put the stress on them without the aid of the roll pins. At that point or when one of the 3 comes completely out it starts shearing things. In the winter with the rotator cold it has a tendency to take out gear teeth but still seem to work. This puts an added strain on the little bolts and roll pins until something gives or works loose. I've got several here to repair and had a good chance to find what made them fail.